A network processor is a device that executes programs to handle packet traffic in a data network. Examples include network processors on router line cards and in other network equipment. The Intel IXP2800 is a multi-threaded multiprocessor integrated circuit that is capable of receiving packets, classifying and performing atomic operations on the packets and packet data, and transmitting packets. Within the IXP2800 integrated circuit, microengines operate on packet data stored in a memory. The memory is accessible to the microengines via a DRAM command/push/pull bus. The IXP2800 architecture is therefore flexible and expandable in that more processing power can be added and coupled to the bus so that the added processors will have access to the memory. A family of network processors of this architecture can be made by providing network processor integrated circuits with different amounts of processing power and with different amounts of memory.